The delayed openings are so employees can take part in a team meeting to discuss changes the company is making to tighten its food safety measures. Chipotle Mexican Grill Inc. also says the company will thank employees for their work in recent weeks.

The chain’s sales have tanked since an E. coli outbreak that came to light at the end of October. Its problem worsened after a norovirus outbreak in Boston in early December sickened dozens.